Tubular pin and method of making same



June 30, 1931. w. J. GAGNON TUBULAR PIN AND METHOD OF .MAKING SAME Filed Sept. ll 1928 N m s ma@ mAh EGW vi im m a M.. mh L@ m W Patented June 30, 1931 UNITED STATES PATENT `oel-lcs WILLIAM J. GAGNON, OF BRIDGEPORT, CONNECTICUT, ASSIGNOR T THE BEAD CHAIN MANUFACTURING COMPANY, OF BRIDGEPORT, CONNECTICUT, A CORPORATION 0F CONNECTICUT TUIBULAR PIN AND METHOD OF MAKINGl SAME- `.Application tiled September `11, 1928. Serial No. 305,296.

pin from sheet metal which will have greati .er strength than the usual pin so construct- .l0 ed at the present time, and the provision of such a pin which will notbe subject to.

leakage into its interior of electrical insulating material `into which it may be molded. Other objects will appear from Il the following description.

Heretofore when' pins formed of sheet metal and closed with a seam have been molded into the insulation forming the base of a radio tube the hydraulic pressure of liquid I0 insulation amounting to 6,000 or 7,000 pounds has been suilicient to cause the head of the in tol open at its seam and allow some ofp the insulation to leak through the `pin into its interior. Since it is customary to pass a wire conductor throughsuch a pin after the pin has been molded into the base of the tube and solderthe end of the conductor to the lower end of the pin, the resence of insulation within the pin is o jectionable. Such material within the in, ob-

structs the assage ofthe conductor t rough the pin. urthermore, the present process of molding pins intoinsulation bases, such for instance as bakelite, makes it necessary to use a conically shaped punch in a process well-known in the art. In this process thepunchsspreads open the seam of the pin as it travels downward to press the insulation into shape thereby causing leakage suflcient to impair the usefulness of the pin.

I have discovered that if the top of the in be given a special shape and if a cup, avlng no seam, be closed over and suitably attached to the pin top, this leakage of insulation may be completely eliminated and a stronger and more useful `pin roduced. One orm of the invention isl i lustrated in the accompanying drawings, in which- Figure 1 illustrates a method of making the capped tubular pin, the apparatus being shown ready to attach the`cup upon .the pin top f .f Fig. 2 shows the parts illustrated in vFigure 1 as the cup is attached to the pin top, Fig. 3 is a sectional elevation of the pin and cup, and

Fig. 4 is an elevation ofthe capped pin with its top unched, the upper part of the pin and cup being shown in section.

In the embodiment of' the invention illustrated in the drawings, there is first formed a sheet metal tubular pin havinv a seam runf y cup 13 somewhat like the metallic shell of a cartridge (best seen in Fig. 3), is inverted and placed over the top of the pin, and its edge is compressed about the neck 12, so that it is solidly attached to the pin.y The relative position of the pin top and cup will be seen in Fig. 4.

The top of the pin is thus capped by the 'cup 13, which strengthens the pin by closely surrounding its' top, and also closes the seam above the abutment shoulder.

A convenient method of capping the pin is illustrated in Figs. 1 and 2 in which the cups 13 are fed from a chute 14 into a feeding slot 15, along which a plunger 16 moves each cup into position over a pin end, while the pin is held in dies 17. The conformation of the die adjaceptthe pin'head is such that the edges of the cup are forced together about the neck as thecup is pushed upon the pin end. Thus the cup is firmly attached to the pin. Fig. 2 shows the position of the cup as che -die forces it into place about the pin en Gapped radio pins constructed in accordance with the invention are admirably suited for bcingmolded into radio tube bases. `As

is well-known, only the top of the in, as far down as the abutment shoulder, 1s molded seam running longitudinall abutment shoulder formed integrally with into the tube base. The pin top being surrounded by an unbroken cup permits no leakage into the pin top of the fluid into which it is molded. Furthermore, when the usual conically-shaped punch is applied to the pin top to open up a wire Way, and press the molded base into shape, it does not open up the seam and' cause leakage into the pin.

Instead it pierces the cup top and makes a perfect valve seat in its downward travel. Leakage of the tube base material into the pin is thus prevented. (See Fig. 4).

Pins constructed in accordance with the present invention, therefore, will be seen to be free from the objections to Which other sheet metal pins are subject, in that the insulation Will not leak into them during the process of molding and their strength Will be suicient for al1 practical purposes. The process of capping the end of the pin is simple, effective and inexpensive, and many ofthe advantages of the solid pin are present in sheet metal pins constructed in accordance with the invention.

With the understanding that the specic description and illustrations are given merely to indicate how the invention may be applied,

I claim:

l. A tubular pin formed of sheet material comprising a'shank having a longitudinal seam therein and an abutment shoulder intermediate of'and unitary with said shank, said shank being necked down on one side of and next to said abutment shoulder, in combinationwith a cup closed over the end of the pin adjacent the necked down portion,

"substantially as described.

2. A sheet metal `tubular pin having a thereof, an

and surrounding said pin, said pin being necked down on one side of and adjacent said abutment shoulder, and a seamless cup capping said pin, the edges of said cup being compressed about the neck.

In testimony whereof I have signed my namev to this specification.

WILLIAM J. GAGNON. 

